Typewriter escapement mechanism



April 11, 1939. KQ'CA 2,153,632

TYPEWRITER ESCAPEMENT MECHANI SM Filed May 18, 1957 40 0 I ae PatentedApr. 11, 1939 UNITED STATES PATENT OFFICE James F. Koca,

Woodstock, Ill.,

assignor to Woodstock Typewriter Company, Woodstock, 111., a corporationof Illinois Application May 18, 1937, Serial No. 143,334

3 Claims.

The present invention relates to a typewriter and more particularly toan escapement mechanism for controlling the spacing of the letters.

7 It is an object of the present invention to provide a new and improvedescapement structure which will tend to eliminate the noise andvibration due to the impact of the elements during operation.

Yet another object of this invention is to provide an escapementstructure for a typewriter in which the normal shock due to the suddenstopping of the carriage is greatly absorbed and which is operative eventhough more than one stop member is actuated to suddenly stop thecarriage.

Numerous other objects and advantages will more fully appear during thecourse and progress of the following specification.

Fig. 1 is a rear elevation of an escapement constructed in accordancewith the present invention.

Fig. 2 is a sectional elevation taken on the line 22 in Fig. 1.

Fig. 3 is a perspective view of a ratchet wheel pinion and associatedpivot constructed in accordance with the present invention.

Fig. 4 is a perspective view of a pivot supporting sleeve made inaccordance with the pres ent invention.

The particular typewriter, herein shown for the purpose of illustratingthe present invention, is the popular, well known Woodstock typewriteralthough the invention is not confined to this particular type ofmachine.

The typewriting machine illustrated in part has a frame ill in which acarriage (not shown) is mounted to move in a transverse direction. Therack I2 is secured to the rear portion of the carriage and extendslongitudinally thereof. 4 Suitable resilient means is, in theconventional manner, secured to the carriage and tends normally to drawthe carriage and rack in the direction of the arrow (see Fig. 1). Thestresses tending to displace the carriage are resisted by the engagementof the rack with a pinion I 4 which is rigidly held from movement in aclockwise direction, as viewed in Fig. l, by the pawl 16 pivoted to anescapement wheel 18 as at 20. The pawl I6 is normally maintained inengagement with the pinion It by means of the spring 22 secured to theescapement wheel. The pawl, however, is so arranged as to freely permitmovement of the pinion i l in the counter-clockwise direction, as viewedin Fig. 1, so that the carriage may be readily returned in the usualmanner against the action of the aforementioned resilient means.

The escapement wheel 18 has a plurality of teeth or projections 24identical in number with the teeth upon the pinion l4 and is mountedupon a fixed pivot 26 for rotation thereabout. The central portion ofthe ratchet wheel extends transversely a considerable distance from theplane of the Web portion 28 to form the bearing sleeve 30. The pinion E4in turn is mounted rotatably upon this cylindrical sleeve 30, as shownmore in detail in Fig. 2, and the parts maintained in assembledrelationship by the machine screw 32 threadedly engaging the pivotaxially thereof.

The pivot 25 is provided with an axially extending, preferablycylindrical shank 34 for fixedly positioning the member, together withthe ratchet wheel and the pinion, with respect to the frame of themachine. To this end the frame is provided with a bore 36 ofsubstantially greater diameter than that of the cylindrical shank 34.Intermediate of the shank 34 and the bore 35, for supporting the latterfirmly in operative relation, is an annular cylindrical sleeve 38composed of some suitable resilient material such as rubber, cork or thelike.

According to one preferred embodiment the sleeve 38 is tightly situatedabout the shank 34 and this assembly forced tightly into the bore 36. Bysuitably proportioning the various elements in the aperture the partswill be held firmly against all normal tendency of displacement. Inorder to additionally maintain the shank 34 in proper operativeposition, a pin 40 may be passed through the shank and sleeve, tightlyjoining the members together.

According to another preferred embodiment the pin 46 may be extendedinto the frame 10, thus serving to join the three elements positively inoperative position. While a pin has been described, it will be obviousthat set screws or various other means might be employed to maintain theparts in proper position without substantially interfering with theresilient mounting of the pivot 26.

The remainder of the escapement mechanism 42 is of a well known type,being supported generally on opposed pivots 44 and controlled by thespace link 46 actuable from the space bar, keys or any other desiredportion of the typewriter for the purpose of controlling the position ofthe stop dogs 48 and 50 with respect to the teeth of the escapementwheel 24.

It will be apparent that the transverse position of the carriage withrespect to the platen is maintained by the forceful engagement of thedog 50 with the adjacent projection or tooth of the escapement Wheel.When the space link is actuated, as, for instance, when a key on thetypewriting machine is pressed, the associated assembly is moved througha short are about the pivots 44, moving the dog 50 rearwardly of themachine until it slides-off the face of the adjacent projection on theescapement wheel 24. Immediately the aforementioned resilient meansdraws the carriage and the rack in the direction indicated by the arrowsin Fig. 1. The pinion l4 engaging the rack I2 is accordingly rotated inthe clockwise direction, as viewed in Fig. 1, as is also the escapementwheel 24 which is secured for uni-directional movement thereto by meansof the pawl [6. Movement of the members ceases when the releasedprojection upon the escapement wheel contacts the dog 48. As the spacelink 46 is released, the dog 50 moves back into the path of the nextsucceeding projection to position the plate accurately one space removedfrom its previous position.

The impingement of the ratchet wheel upon either or both of the dogs 48and 50 under the influence of the inertia of the carriage, as well asthe resilient means tending to draw it in the aforementioned direction,is normally a source of vibration and noise. During each spacing stepthe carriage, after being released by the dogs and given some momentumby the resilient means, is again stopped in such a manner that themomentum must be substantially instantaneously dissipated. This normallyresults in the creation of relatively high instantaneous impact forces.

The present invention provides a means whereby such shocks are largelyabsorbed and the operation of the typewriter rendered increasinglysmooth, silent and efficient. At the'same time the elements of theescapement mechanism remain always in proper relative position. Thus,while supported with some degree of resiliency, the pivot 26 isnevertheless always maintained properly centered with respect to theaperture 36 in the frame 10 and accordingly cooperates with theremainder of the spacing control in the usual manner.

It is thought that the invention and numerous of its attendantadvantages will be understood from the foregoing description and it isobvious that numerous changes may be made in the form, construction andarrangement of the several parts without departing from the spirit orscope of the invention, or sacrificing any of its attendant advantages,the form herein described being a preferred embodiment for the purposeof illustrating the invention.

I claim:

1. In a typewriter having a frame and a carriage, an escapement wheel, astop member associated with the wheel for positioning the carriage, apivot upon which the wheel is mounted for rotation with respect to theframe, said pivot being mounted on the frame, and a resilient sleevesurrounding a portion of the pivot and being interposed between thepivot and the frame whereby to provide a cushion.

2. In a typewriter having a frame, a carriage, a rack on the carriageand normally engaging a pinion, an escapement wheel associated with saidpinion, a stop means engaging the wheel for positioning the carriage, apivot pin supporting the wheel for rotation thereabout, said pin havingan extension mounted fixedly in the frame, and a resilient sleevesurrounding the extension and supporting the pin in operative positionin the frame whereby to resiliently center the pivot.

3. In a typewriter having a frame, a carriage and a spacing mechanismcomprising an escapement wheel, escapement wheel mounting meanspivotally supporting said escapement wheel for rotation with respect tothe frame, said escapement wheel mounting means being mounted on thesaid frame, stop means adapted to engage the escapement wheel forpositioning the carriage, said stop means being operatively supported onthe said frame, and resilient means interposed between said escapementwheel mounting means and the typewriter frame to absorb impact andresiliently support the mechanism, said supporting means for said stopmeans being independent of said resilient means whereby to permitresilient absorption of impact vibrations by said resilient meansrelative to said coacting stop means.

JAMES F. KOCA.

